Why Finger Multiplication Works

In the Finger Multiplication post, we have learned how we can cleverly multiply numbers from 6 to 10 using  our fingers without memorizing the multiplication table. In this post, we will discuss the reason why this method works.  The proof can be written in a few lines, but since this article falls under the elementary school mathematics category, we will discuss it with more details.

Finger Multiplication of 8 x 7.

Let’s examine the first example in the previous article as shown above. In the example, we wanted to multiply 8 by 7, so we connected the ring and the middle fingers. In this discussion, we will call the connected fingers and all the fingers below them down fingers, while we call all the fingers above them up fingers. » Read more

Finger Math Multiplication

I was surprised when I came across with an article on Polish hand magic, a strategy for multiplication using fingers. I remember us doing it when we were in the first grade, but in a slightly different way.  Here in our country, we call it Finger Math or Finger Multiplication.

Finger multiplication is a strategy for multiplying numbers from 6 to 10.  It is used by pupils in the early grades who have not memorized the multiplication table yet.  The idea is to assign the numbers from 6 to 10 to each finger on both hands (see Figure 1): 6 to the pinkie, 7 to the ring finger, 8 to the middle finger, 9 to the index finger, and 10 to the thumb.

Figure 1

To multiply, do the following (see Figure 2):

(1) Connect the fingers assigned to the numbers that you want to multiply. For example, in multiplying 8 and 7, connect the middle finger and the ring finger (see Figure 2). » Read more

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